1. Field of Invention
The field of invention is industrial spraying equipment to clean, rinse, and/or chemical-treat articles of manufacture. The spraying takes place in a confined area, such as a spray or washer booth, in which various liquids are piped under pressure through overhead or bottom feed pipes, called headers, into a plurality of vertical pipes, called risers, connected to the headers, and then out through nozzles which are attached to the risers and which are adapted to spray workpieces in the washer booth.
2. Description of Related Art
Prior art washer booths are customarily made of steel, and are basically rectangular, with means for a parts conveyor to pass through. They are oftentimes equipped with a pair of plastic or steel header pipes spaced apart and running parallel and longitudinal to the washer booth floor or ceiling. Industrial liquids are stored in a tank underneath the washer booth floor and pumped through suitable plumbing to the headers. A bank of plastic or steel risers is connected to each header, extending vertically upward or downward along an adjacent washer booth wall. Extruded chlorinated polyvinylchloride (CPVC) is the state-of-the-art plastic commonly used for headers and risers. Several nozzles are secured to each riser of each bank of risers and are aimed inwardly to spray workpieces being conveyed between opposed banks of risers.
The spraying nozzles may be as simple as holes drilled in the risers, but mere holes have proved unsatisfactory for most industrial applications because they are difficult to clean, provide virtually no spray pattern, and are impossible to adjust. As a consequence, a three-part glass fiber or glass bead reinforced polyolefin nozzle has been developed comprising a body, a spraying tip, and a threaded nut to secure the tip to the body. The body has a part adapted to fit in a hole drilled in the riser, and the body is clamped to the riser by a quick release spring clamping mechanism. The body has an interior truncated spherical cavity in which a matching truncated spherical portion of the nozzle tip is adapted to fit for ball and socket swivel movement within the cavity. The exterior of the body is threaded to engage the tip securing threaded nut, referred to in the industry as a cap.
The polyolefin spray nozzle just described is now the standard of the industry and is readily available from many spray nozzle manufacturers. It is adjustable and is quickly removable from a riser for cleaning or changing the tip. To date it has been adequate for low pressure spraying applications in the range of 10 to 30 psi. However, the quick release spring clamp is relatively weak, and does not prevent leaking between the riser and the nozzle body. In applications where higher pressures above 30 psi, are required, leaking increases proportionately. In such applications, this type of spray nozzle is therefore unsuitable.
When pressures are high enough to cause leaking between the riser and the nozzle body, leaking also usually occurs between the nozzle body cavity and the mating truncated spherical portion of the nozzle tip. Further, when this occurs, leaking between the nozzle tip and the nozzle cap may also occur. In most applications, this leaking is tolerated only because there is no better nozzle available. However, the demand in the industry is increasingly for higher spraying pressures for spraying applications not possible with presently known nozzles.
In the present state of the art, risers have universally been made cut to length from a single longer piece of CPVC pipe, which results in considerable unusable scrap, since CPVC cannot be recycled for any purpose. If the riser becomes chemically obstructed, the entire riser must be disassembled in order to remove the obstruction. If any portion of the riser should be defective, the entire riser must be scrapped. Since the locations of nozzles on risers must be predetermined and pre-drilled, thereafter the only means to adjust the spray is by the limited available movement of the nozzle spray tip. A single nozzle, per se, cannot be shifted vertically or horizontally to another quadrant of the riser without shifting the entire riser, in which event all of the other nozzles must be similarly shifted.
Chlorinated polyvinylchloride (CPVC) is not compatible with polyolefins, in that the two plastics cannot be glued, welded, molded, or otherwise bonded together. Accordingly, molded glass-filled polyolefin spray nozzles must be secured to extruded CPVC risers with brackets or by threading. It is not feasible to mold CPVC risers because of the high cost of tooling, and the nature of the process is labor intensive. Extruded CPVC pipe is relatively inexpensive, both in labor and tooling cost, however. CPVC risers are limited to washer booth operations in which the temperature of the bath does not exceed 180.degree.. For similar reasons of economy, polyolefins have not been used for risers because the plastic must be glass-filled for strength, and glass-filled polyolefins are not extrudable.